(1) Field of the Invention
This invention relates to automatic analyzing apparatus for dispensing reagents selected according to examination items of specimens to cause reactions, and measuring and analyzing reaction mixtures resulting from a plurality of analytic processes. More particularly, the invention relates to an automatic analyzing apparatus for conducting examination on a plurality of items in parallel.
(2) Description of the Related Art
Conventional automatic analyzing apparatus have a construction based on a rotary disk system as disclosed in Japanese Patent Publications (Unexamined) Nos. 3-48161, 3-233362 and 3-186763, for example. Specifically, such an apparatus includes a specimen table, varied reagent tables, and an optical unit such as a photometric unit, absorptiometric unit or fluorophotometric unit, arranged according to analytic processes around a disk-shaped reaction table. The reaction table is rotated intermittently by predetermined amounts to transport reaction vessels placed peripherally of the reaction table to positions opposed to the respective units. In these positions specimens and reagents are placed in the vessels, and reaction mixtures are measured.
An exemplary case of analyzing 20 specimens with respect to three items (KK1, KK2 and KK3) will particularly be described with reference to FIG. 1. In this example, three reagents are successively dispensed for one analysis.
A reaction vessel supply mechanism, not shown, successively supplies reaction vessels P to peripheral positions on an upper surface of a disk-shaped reaction table 1. With intermittent rotation by predetermined amounts of the reaction table 1, the reaction vessels P placed thereon move successively through positions opposed to a specimen table 2 and reagent tables 3, 4 and 5 to a position opposed to a photometric unit 6.
The rotatable specimen table 2 supports 20 specimen vessels R1-R20 holding specimens S1-S20 to be analyzed, and specimen vessels RS1-RS3 holding sample specimens SS1-SS3 for use in an analytical curve correction to be described later. A movable nozzle 72 successively dispenses the specimens S1-S20 (when analyzing these specimens) or SS1-SS2 (when correcting analytical curves) into the respective reaction vessels P transported to the position opposed thereto.
Each of the rotatable reagent tables 3, 4 and 5 supports three reagent vessels Q31-Q33 holding reagents X31-X33, reagent vessels Q41-Q43 holding reagents X41-X43, or reagent vessels Q51-Q53 holding reagents X51-X53, for the respective analytic items KK1, KK2 and KK3. A movable nozzle 73, 74 or 75 successively dispenses the reagents X31-X33, X41-X43 or X51-X53 into the respective reaction vessels P transported to the position opposed thereto.
When analyzing the specimens, for example, the first reaction vessel P1 (for analytic item KK1) supplied to the reaction table 1 receives specimen S1 from the specimen table 2, reagent X31 from the reagent table 3, reagent X41 from the reagent table 4, and reagent X51 from the reagent table 5. The second reaction vessel P2 (for analytic item KK2) supplied to the reaction table 1 receives specimen S1 and reagents X32, X42 and X52. The third reaction vessel P3 (for analytic item KK3) receives specimen S1 and reagents X33, X43 and X53. The fourth reaction vessel P4 (for analytic item KK1) receives specimen S2 and reagents X31, X41 and X51. Thus, each of the specimens S1-S20 is placed in three of the reaction vessels P1-P60. Three reaction vessels (e.g. P1-P3) holding the same specimen (e.g. S1) are used in the analysis with respect to the three items (KK1, KK2 and KK3). Each of these reaction vessels (P1-P3) successively receives reagents for use in one analysis (for example, the reaction vessel P1 receives reagents X31, X41 and X51, the reaction vessel P2 receives reagents X32, X42 and X52, and the reaction vessel P3 receives reagents X33, X43 and X53.
The photometric unit 6 takes measurement, through each reaction vessel P, of a reaction mixture having completed a reaction therein. Based on a quantity of light (i.e. light emission from the reaction mixture) measured, the specimen is analyzed by determining the concentration of an objective component of the specimen.
The reaction vessels P having completed photometry are removed from the reaction table 1 by a discharge mechanism not shown. These vessels are cleaned for repeated use.
The reagent tables 3, 4 and 5 and photometric unit 6 are arranged and the intermittent rotation of the reaction table 1 is controlled to secure appropriate reaction periods. Consequently, a period of reaction between specimens S1-S20 and reagent X31 (X32 or X33) corresponds to a period of time from the dispensation of reagent X31 (or X32 or X33) in the position opposed to the reagent table 3 to the dispensation of reagent X41 (X42 or X43) in the position opposed to the reagent table 4, with rotation of the reaction table 1 occurring therebetween. Similarly, a period of reaction between specimen and reagent corresponds to a period of time from reagent table 4 to reagent table 5, or from reagent table 5 to photometric unit 6.
A way in which analytical curves are corrected with the analyzing apparatus having the above construction will be described next. The analytical curve refers to a relationship between a quantity of light emission determined through photometry from the reaction mixture resulting from dispensation of a predetermined reagent to a specimen and concentration of an objective component of the specimen. Correction of the analytical curve means correction of such a relationship.
Specifically, the analytical curve is the relationship between a quantity of light emission and concentration of an objective component of a specimen as represented by the solid line in FIG. 2. The analytical curve is used to derive concentration (e.g. x%) of an objective component of the specimen from a quantity of light emission (e.g. Lx) measured by the photometric unit 6.
However, the analytical curve can be inaccurate depending on the examination environment. To obtain a proper analytical curve, it is necessary to analyze a sample specimen prior to analyzing the objective specimen and correct a known analytical curve based on results of the analysis.
For example, the known analytical curve (solid line in FIG. 2) shows that a specimen of 50% concentration gives light emission L50. Assume that a sample specimen (50% concentration) gives light emission L'50. In this case, a new analytical curve is obtained by multiplying the light emission of the known analytical curve by L'50/L50. The new analytical curve obtained in this way is represented by the dotted line in FIG. 2. To carry out an accurate correction of the analytical curve, it is recommendable to use many sample specimens.
The case of conducting analysis on three items (KK1, KK2 and KK3) will now be considered.
As shown in FIG. 1, three reaction vessels P (PS1, PS2 and PS3) are successively supplied to the reaction table 1 prior to analyzing the objective specimens. When the reaction vessels PS1, PS2 and PS3 reach the specimen table 2, sample specimens SS1 (for analytic item KK1), SS2 (for analytic item KK2) and SS3 (for analytic item KK3) are dispensed into the reaction vessels PS1, PS2 and PS3, respectively. The reaction vessels PS1, PS2 and PS3 holding the sample specimens SS1, SS2 and SS3 then receive reagents corresponding to the respective analytic items from each of the reagent tables 3, 4 and 5. Thereafter the photometric unit 6 measures each of the sample specimens SS1, SS2 and SS3. Finally, as described hereinbefore, an analytical curve is corrected for each analytic item based on the result of photometry.
As noted hereinbefore, it is desirable to use many sample specimens in order to assure an accurate correction of the analytical curve. If, for example, two sample specimens are used for each analytic item, six reaction vessels P are used and each of the sample specimens SS1-SS3 is placed in two of each of the reaction vessels P. If three sample specimens are used for each analytic item, nine reaction vessels P are used.
However, the conventional automatic analyzing apparatus described above has the following drawbacks.
The drawbacks of the entirety of the apparatus will be cited first. Firstly, the conventional apparatus requires the specimen table 2, varied reagent tables 3, 4 and 5 and photometric unit 6 to be arranged around the reaction table 1. Thus, the apparatus has the disadvantage of being large (i.e. occupying a large floor area). With an increase in the number of reagents or in the number of items on which analysis is carried out, the reaction table 1 must be enlarged correspondingly, thereby occupying a still larger amount of floor space.
Secondly, the arrangement of specimen table 2, varied reagent tables 3, 4 and 5 and photometric unit 6 is designed, and the rotation of the reaction table 1 is controlled, according to the analytic items. To carry out analytic processes involving different reaction periods, for example, the arrangement of tables 2, 3, 4 and 5 and photometric unit 6 must be altered or the reaction table 1 must be rotated in different intermittent amounts. Further, where it is desired to change some of the reaction periods, the reagent tables or other components must be rearranged since a change in the intermittent rotation of the reaction table 1 would affect other reaction periods. Thus, the apparatus tends to perform only a single function, and lacks in versatility with respect to analyzing items and analyzing process conditions.
Thirdly, when a plurality of specimens are analyzed in parallel, it is difficult for the following reason to insert a specimen requiring an urgent treatment between the specimens being processed. Inserting a specimen requiring an urgent treatment between the specimens to which reagents have already been added is impossible since it would seriously affect the specimens being processed such as delaying the reaction time of the specimens to which the reagents have been added. If a specimen requiring an urgent treatment were inserted between other specimens before adding reagents thereto, the specimens and results of analysis could not be matched since the specimens are identified according to the order of treatment. A shift may be made in identification of the specimens to accommodate a specimen requiring an urgent treatment. However, each of the specimens following the inserted specimen must be shifted on the reaction table 1, for example, since otherwise these subsequent specimens could not be identified correctly. Such an insertion would necessitate a troublesome rearranging operation. Thus, it is simplest to put the specimen requiring an urgent treatment at the end of the specimens subjected to the analytic processes. This results in no urgent treatment.
Fourthly, in analyzing a plurality of specimens with respect to a plurality of items in parallel, the conventional apparatus carries out the analytic processes independently of one another, using the reaction vessels corresponding in number to the number of specimens multiplied by the number of items. It is difficult to reduce the processing time required to analyze all of the specimens.
The conventional apparatus has the following drawbacks relating to the dispensing units for dispensing reagents. Firstly, it is inevitable in the conventional apparatus to disperse the reagent vessels holding reagents, and movable nozzles are used for this reason. With an increase in the number of reagents, the number of movable nozzles must also be increased. Then the apparatus must be equipped with a plurality of nozzle drive mechanisms. This results in a complicated construction of the apparatus.
Secondly, certain reagents must be preserved in cold storage, and it is inefficient and uneconomical to keep such reagents in cold storage in a dispersed way as practiced heretofore since one apparatus must include a plurality of refrigerating mechanisms. Further, with the conventional movable nozzle system in which the nozzles make direct access to the reagent vessels, it is difficult to refrigerate the reagents in one place.
Thirdly, the movable nozzles make direct contact with the reagents in the reagent vessels, and covers of the reagent vessels must be kept open to allow access. As a result, the reagents could easily be contaminated or lost through evaporation.
Furthermore, the conventional apparatus has the following drawbacks relating to the optical unit. Firstly, the conventional optical unit carries out measurement of the reaction mixtures remaining in the reaction vessels. Even a slight stain on a surface of a reaction vessel would vary transmittance, thereby rendering accurate measurement impossible.
Secondly, the conventional optical unit takes measurement with a reaction vessel placed opposite a photodetecting element thereof. A slight deviation occurring when the reaction vessel is transported to the optical unit could result in a relative displacement between the vessel and photodetecting element. This makes uniform photometry impossible.
Thirdly, in the conventional apparatus, the reaction table 1 transports one reaction vessel after another to the photometric unit for measurement. Where, for example, a plurality of reaction vessels are subjected to photometry in parallel in order to reduce the processing time, it is difficult to maintain the photometric independence of each reaction vessel.
Fourthly, the conventional optical unit must have an inlet and an outlet for the reaction vessels to move into and out of the optical unit. Accurate photometry is impossible since it is difficult to seal off ambient light entering through the inlet and outlet.
There is a further drawback relating to the correction of an analytical curve. In order to correct the analytical curve accurately, it is necessary to use many sample specimens, which requires a correspondingly large number of reaction vessels. A processing time spent for the analytical curve correction corresponds to a period from the time at which the first reaction vessel for use in the analytical curve correction is delivered to the reaction table to the time at which the last reaction vessel used in the analytical curve correction is removed from the reaction table. Thus, an extended processing time is required to correct the analytical curve accurately.